Surgical stapling loading unit with stroke counter and lockout

ABSTRACT

A surgical loading unit for use with a handle assembly includes an elongate outer frame, an end effector mounted to a distal end of the outer frame, a drive at least partially disposed within the outer frame and operatively coupled to the end effector, and a rotatable counter mounted to the outer frame and adapted for rotational movement about the longitudinal axis. A counter actuator is mounted to the drive and dimensioned to engage the rotatable counter to cause rotational movement of the rotatable counter through an arc segment of rotation during each firing stroke of the drive.

BACKGROUND

1. Technical Field

The present disclosure relates to a surgical stapling apparatus, andmore particularly, relates to a surgical stapling loading unit having afiring stroke counter and a lockout which locks the loading unit uponcompletion of a predefined number of firing strokes.

2. Background of Related Art

Surgical staplers for stapling tissue are known in the art and areinclusive of both single use and multiple use devices. Single usedevices are preloaded with one or more staples and are disposed after asingle use. Multiple use devices are disposed upon exhaustion of thesupply of staples or completion of the surgical procedure. If the supplyof staples is exhausted prior to completion of a surgical procedure, anew surgical stapler may be required to complete the surgical procedure.The use of additional surgical staplers for a single surgical procedurecan be expensive.

In order to address the high expense associated with the use of multiplesurgical staplers for a single procedure, surgical staplers withreplaceable staple cartridges have been developed.

Certain instruments include a surgical stapling handle assembly and asurgical loading unit. The loading unit may be a single use loading unit(SULU) or a multiple use loading unit (MULU). The loading unit includesa body and an end effector, and is attached to the handle assemblyimmediately prior to surgery. The end effector may include a cartridgewhich houses a plurality of staples. After use, the loading unit can beremoved relative to the handle assembly and replaced with a new loadingunit to perform additional stapling and/or cutting operations. A driveassembly is supported within the loading unit and is engagable with acontrol rod of the surgical handle assembly to control operation of theloading unit.

Although these systems have provided significant clinical benefits,improvements are still possible. For example, it would be desirable toprovide an improved stapling loading unit for use in a surgical staplingsystem which tracts the staple firing sequence to assist the clinicianin monitoring the staple supply. It also would be beneficial to providea surgical stapling device having a lockout to prevent firing of thedevice after the staple supply has been depleted.

SUMMARY

Accordingly, the present disclosure is directed to a surgical loadingunit for use with a handle assembly. The surgical loading unit includesan elongate outer frame defining a longitudinal axis and having proximaland distal ends, an end effector mounted to the distal end of the outerframe, a drive at least partially disposed within the outer frame andoperatively coupled to the end effector, and being adapted forlongitudinal movement through a plurality of sequential firing strokesto operate the end effector, and a rotatable counter mounted to theouter frame and adapted for rotational movement about the longitudinalaxis. The rotatable counter has visual indicators for providing visualindicia corresponding to a number of firing strokes completed by thedrive. A counter actuator is mounted to the drive and dimensioned toengage the rotatable counter to cause rotational movement of therotatable counter through an arc segment of rotation during each firingstroke of the drive. A cam actuator is mounted to the drive anddimensioned to operatively engage the counter actuator to cause releaseof the counter actuator from the rotatable counter upon longitudinalmovement of the drive through each successive return stroke. Inembodiments, the outer frame defines a window through which a visualindicator of the rotatable counter is visible.

In some embodiments, the rotatable counter includes a stop which ispositionable to engage the drive upon rotatable movement of therotatable counter through a predetermined number of arc segmentscorresponding to a predetermined number of firing strokes completed bythe drive.

The rotatable counter may include internal helical grooves which areengaged by the counter actuator to cause rotational movement of therotatable counter during each firing stroke of the drive. Inembodiments, the counter actuator is adapted to pivot relative to thedrive between an engaged position to be received within one of thehelical grooves of the rotatable counter during each firing stroke ofthe drive and at least a disengaged position disengaged from the one ofthe helical groove during each return stroke of the drive. The counteractuator may be normally biased toward the engaged position.

In other embodiments, the cam actuator is adapted to pivot between aninitial position and first and second pivoted positions. The camactuator permits the counter actuator to assume the engaged position ofthe counter actuator when the cam actuator is in the first pivotedposition, and moves the counter actuator to the disengaged position ofthe counter actuator when the cam actuator is in the second pivotedposition. The cam actuator may be normally biased toward the initialposition, and pivot in a first direction to assume the first pivotedposition and pivot in a second direction to assume the second pivotedposition.

The outer frame may include a cam having rear and forward cam surfaces.The cam actuator is dimensioned to engage the rear cam surface duringmovement of the drive through each firing stroke to move the camactuator to the first pivoted position thereby permitting the counteractuator to assume the engaged position. The cam actuator is dimensionedto engage the forward cam surface during movement of the drive througheach return stroke to orient the cam actuator in the second pivotedposition thereby moving the counter actuator to the disengaged position.

In certain embodiments, the loading unit includes a detent mechanismhaving a detent member mounted relative to the outer frame and lockingrecesses associated with the rotatable counter. The detent member isengagable with a respective locking recess subsequent to each firingstroke of the drive to maintain the rotatable counter at a desiredrotational position, and adapted to release the respective lockingrecess upon movement of the drive through each successive firing stroke.

In embodiments, the end effector includes a fastener assembly having aplurality of fasteners where at least one fastener is ejected uponmovement of the drive through a firing stroke. The fasteners can besurgical staples, two-part fasteners or other types.

In another embodiment, a surgical loading unit for use with a handleassembly includes an elongate outer frame defining a longitudinal axisand having proximal and distal ends, a staple assembly mounted to thedistal end of the outer frame and having a staple cartridge and ananvil, a drive at least partially disposed within the outer frame andoperatively couplable to the staple assembly, and being adapted forlongitudinal movement through a plurality of sequential strokes to ejectat least one staple from the staple cartridge for crimping by the anvil,and a rotatable counter and lockout mechanism. The rotatable counter andlockout mechanism includes a rotatable counter mounted to the outerframe and adapted for rotational movement through an arc segment ofrotation upon movement of the drive through each firing stroke, at leastone visual indicator associated with the rotatable counter for providingvisual indicia corresponding to a number of firing strokes completed bythe drive, and a lock member positionable to engage the drive uponrotatable movement of the rotatable counter through a predeterminednumber of arc segments corresponding to a predetermined number of firingstrokes completed by the drive. The rotatable counter and lockoutmechanism further includes a counter actuator mounted to the drive anddimensioned to engage the rotatable counter to cause rotational movementof the counter through an arc segment of rotation during each firingstroke of the drive and a cam actuator mounted to the drive anddimensioned to operatively engage the counter actuator to cause releaseof the counter actuator from the rotatable counter upon longitudinalmovement of the drive through each successive return stroke.

In some embodiments, the counter actuator is adapted to pivot relativeto the drive between an engaged position to couple with the rotatablecounter during each firing stroke of the drive and at least a disengagedposition disengaged from the rotatable counter during each return strokeof the drive. In certain embodiments, the rotatable counter includesinternal helical grooves. The counter actuator is engagable with onehelical groove when in the engaged position to cause rotational movementof the rotatable counter during each drive stroke, and disengaged fromthe one helical groove when in the disengaged position during eachreturn stroke.

In embodiments, the cam actuator is adapted to pivot between an initialposition and first and second pivoted positions. The cam actuator isadapted to permit the counter actuator to assume the engaged position ofthe counter actuator when the cam actuator is in the first pivotedposition, and moves the counter actuator to the disengaged position ofthe counter actuator when the cam actuator is in the second pivotedposition.

In certain embodiments, the loading unit includes a detent mechanismhaving a detent member mounted relative to the outer frame and lockingrecesses associated with the rotatable counter. The detent member isengagable with a respective locking recess subsequent to each firingstroke of the drive to maintain the rotatable counter at a desiredrotational position, and adapted to release the respective lockingrecess upon movement of the drive through each successive firing stroke.

Further details and advantages of the outer and inner elastic memberswill be appreciated from the following written description.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the disclosureand, together with a general description of the disclosure given aboveand the detailed description of the embodiments given below, serve toexplain the principles of the disclosure, wherein:

FIG. 1 is a perspective view of a surgical loading unit for performing asurgical stapling procedure in accordance with the principles of thepresent disclosure;

FIG. 2 is a perspective view of the surgical loading unit mounted to asurgical handle assembly;

FIG. 3 a perspective view of the surgical loading unit with portionsremoved illustrating the central drive and the counter and lockoutmechanism mounted relative to the central drive;

FIG. 4 is an enlarged isolated view of the area of detail identified inFIG. 3 illustrating the rotatable counter, the counter actuator and thecam actuator of the counter and lockout mechanism;

FIG. 5 is an exploded perspective view of the loading unit;

FIGS. 6-7 are perspective views of the rotatable counter of the counterand lockout mechanism;

FIG. 8 is a side cross-sectional view of the counter and lockoutmechanism mounted relative to the outer frame;

FIG. 9 is an enlarged isolated view of the area of detail identified inFIG. 1 illustrating the window for viewing the visual indicators;

FIG. 10 is an enlarged isolated view of the area of detail identified inFIG. 5 illustrating the actuator holder and the counter and camactuators of the counter and lockout mechanism;

FIGS. 11A-11B are perspective views of the counter and cam actuators,and the torsion springs of the counter and lockout mechanism;

FIG. 12 is an exploded perspective view illustrating the actuatorholder, the counter and cam actuators and the torsion springs of thecounter and lockout mechanism;

FIG. 13 is a perspective view of a detent mechanism for releasablysecuring the rotatable counter at select positions;

FIG. 14 is a cross-sectional view of another embodiment of a detentmechanism associated with the rotatable counter;

FIG. 15 is a cross-sectional view taken along the lines 15-15 of FIG. 8illustrating an initial stage of the counter and lockout mechanism;

FIG. 16 is an enlarged view of the area of isolation identified in FIG.15;

FIG. 17 is a cross-sectional view similar to the view of FIG. 15illustrating the counter and lockout mechanism upon initiation of afiring stroke of the central drive;

FIG. 18 is an enlarged view of the area of isolation identified in FIG.17;

FIG. 19 is a cross-sectional view similar to the view of FIG. 17illustrating the counter actuator traversing a helical groove of therotatable counter during the firing stroke of the central drive;

FIG. 20 is a perspective view illustrating rotation of the rotatablecounter during the firing stroke of the central drive;

FIG. 21 is a cross-sectional view similar to the view of FIG. 19illustrating completion of the firing stoke of the central drive;

FIG. 22 is an enlarged view of the area of isolation identified in FIG.21;

FIG. 23 is a cross-sectional view similar to the view of FIG. 21illustrating the counter and lockout mechanism during a return stroke ofthe central drive;

FIG. 24 is an enlarged view of the area of isolation identified in FIG.23;

FIG. 25 is a side cross-sectional view of the counter and lockoutmechanism illustrating the rotatable counter in a lock position with aninternal stop on the rotatable counter in engagement with a lock shelfof the central drive to lock the central drive;

FIG. 26 is a perspective view further illustrating the relationship ofthe internal stop of the rotatable counter and the central drive when inthe lock position of the rotatable counter;

FIGS. 27-28 are cross-sectional views of the staple assembly with thestaple cartridge and the anvil in respective open and approximatedconditions;

FIG. 29 is an enlarged side cross sectional view of the staple assemblyillustrating the staples fired from the staple cartridge during a firingstroke; and

FIG. 30 is a side cross-sectional view of the staple assemblyillustrating the staples fired upon completion of the firing stroke.

DETAILED DESCRIPTION OF EMBODIMENTS

Particular embodiments of the present disclosure are describedhereinbelow with reference to the accompanying drawings; however, it isto be understood that the disclosed embodiments are merely examples ofthe disclosure and may be embodied in various forms. Well-knownfunctions or constructions are not described in detail to avoidobscuring the present disclosure in unnecessary detail. Therefore,specific structural and functional details disclosed herein are not tobe interpreted as limiting, but merely as a basis for the claims and asa representative basis for teaching one skilled in the art to employ thepresent disclosure in virtually any appropriately detailed structure.

Referring now to the drawings where like reference numerals indicatesimilar components throughout the several views, FIGS. 1-2 illustratethe surgical loading unit 10 in accordance with the principles of thepresent disclosure. In FIG. 1, the surgical loading unit 10 is depictedin isolation while in FIG. 2 the surgical loading unit 10 is depictedconnected to a surgical handle assembly 200. The surgical loading unit10 and the surgical handle assembly 200 form a surgical system adaptedto perform a surgical procedure on tissue. The loading unit 10 includesan end effector 300 which, in one embodiment, is a stapling assemblyadapted to staple tissue. The loading unit 10 may be a multi-use loadingunit (MULU) adapted, e.g., for sequential or multiple firing of one ormore staples in a linear arrangement.

The surgical handle assembly 200 may be any handle assembly having atleast one actuator, and in some embodiments, two or more actuatorsadapted to control operation of the loading unit 10. It is contemplatedthat the surgical handle assembly 200 may be reusable, i.e., it can bereused with a plurality of loading units 10, and may be used withloading units having different stapling functions such as, e.g.,circular stapling of tissue. The end effector 300 (shown in phantom inFIG. 1) may include a staple cartridge 302 which houses a plurality ofstaples and an anvil 304. The staple cartridge 302 and the anvil 304 aremovable relative to each other between open and approximated positions.Staples are driven from the staple cartridge 302 through tissue andcrimped by the anvil 304. Further details of the handle assembly 200 andthe end effector 300 will be discussed in greater detail hereinbelow.

Referring now to FIGS. 3-5, in conjunction with FIG. 1, the loading unit10 includes an elongate outer member or frame 12 defining a longitudinalaxis “k” and proximal and distal ends 14, 16. In FIGS. 3-4, half of theouter frame 12 is removed for illustrative purposes. The proximal end 14of the outer frame 12 includes a handle mount 18 (FIG. 1) with at leastone mounting tab 20 which couples with the handle assembly 200. Thedistal end 16 of the outer frame 12 supports the end effector 300(removed in FIGS. 3-5). A central beam or drive 22 is at least partiallydisposed within the outer frame 12. The central drive 22 is adapted forlongitudinal movement within the outer frame 12 and is operativelycouplable, at its proximal end, to an actuator of the handle assembly200 and, at its distal end, to the end effector 300. The central drive22 advances or moves distally, during a firing stroke, to control theend effector 300, e.g., by causing the firing of one or more staples.Subsequent to a firing stroke, the central drive 22 moves proximally,during a return stroke, to be in position for another firing sequence.The central drive 22 includes an actuation sled 24 at its distal end 16and a knife 26 to sever tissue, e.g., during the stapling process. Theknife 26 may be a component of, or coupled, to the actuation sled 24.The outer frame 12 may include a translating rod 28 extending along thelongitudinal axis “k”. The translating rod 28 may be coupled to anactuator of the handle assembly 200 and to the end effector 300. Thetranslating rod 28 may move in a longitudinal direction to controlarticulation (e.g., pivoting movement) of the end effector 300.

Referring now to FIGS. 3-7, the loading unit 10 includes a counter andlockout mechanism 30 for tracking the number of firings or firingstrokes completed by the central drive 22 and lock the loading unit 10upon completion of a predetermined number of firing strokes. The counterand lockout mechanism 30 includes a rotatable counter 32 and an actuatorassembly 34. The rotatable counter 32 is adapted for rotational movementabout the longitudinal axis “k” and within the outer frame 12. In oneembodiment, the outer frame 12 defines an internal annular recess 36(FIG. 5) which is dimensioned to receive the rotatable counter 32 in amanner permitting rotational movement of the rotatable counter 32 whilerestricting axial movement. As depicted in FIG. 8, the annular recess 36may include a pair of annular ribs 38, which are received withincorresponding dimensioned annular grooves 40 (FIG. 6) disposed on theexternal wall 32 e of the rotatable counter 32, to assist in securingthe rotatable counter 32 and preventing the rotatable counter 32 frommovement in an axial direction.

With particular reference to FIGS. 6 and 7, the rotatable counter 32 mayinclude a helical gear defining a plurality of internal helical threadsor grooves 42. Each internal helical groove 42 longitudinally extendsalong the length of the rotatable counter 32 in oblique relation withrespect to the longitudinal axis “k”. The internal helical grooves 42may encompass one-half the inner diameter or dimension of the inner wall32 i of the rotatable counter 32 while the remaining portion of theinner wall 32 i is mostly smooth. The rotatable counter 32 may havetwelve internal helical grooves 42 although more or less than twelveinternal helical grooves 42 are also envisioned. The helical grooves 42may be identical such when engaged by the actuator assembly 34 therotatable counter 32 rotates through the same incremental arc segment ofrotation.

The rotatable counter 32 includes visual indicia or indicators 44 on itsexternal wall 32 e. The indicators 44 may include a plurality ofnumbers, e.g., 1-12, corresponding to a number of times the centraldrive 22 completes a firing stroke. Alternatively, the number maycorrespond to the number of firing strokes remaining with the loadingunit 10. The indicators 44 are visible through a window 46 defined inthe outer frame 12 (FIGS. 1 and 9). Upon movement of the central drive22 through a firing stroke, the rotatable counter 32 is rotated topresent the next subsequent indicator 44 for visualization through thewindow 46.

With continued reference to FIGS. 6 and 7, the rotatable counter 32includes an internal stop 48 depending inwardly from the inner wall 32 iof the rotatable counter 32 in diametrical opposed relation to theinternal helical grooves 42. The internal stop 48 is positionable toblock advancement of the central drive 22 upon rotation of the rotatablecounter 32 to a predefined angular orientation, e.g., to lockout thecentral drive 22 upon movement through a predefined number of firingstrokes, which may correspond to depletion of, e.g., the staples in theend effector 300.

Referring now to FIGS. 4 and 10-12, the actuator assembly 34 of thecounter and lockout mechanism 30 will be discussed. The actuatorassembly 34 includes an actuator holder 50, a first top or counteractuator 52 and a second bottom or cam actuator 54. The counter and canactuators 52, 54 are at least partially disposed within a channel 56 ofthe actuator holder 50. The actuator holder 50 is supported within alongitudinal opening 58 of the central drive 22 in fixed relationtherewith (see also FIG. 5). Any methodologies for securing the actuatorholder 50 within the opening 58 of the central drive 22 are envisioned.In one embodiment, the actuator holder 50 includes spaced longitudinalgrooves or rails 60 which receive mounting segments 22 m of the centraldrive 22. The mounting segments 22 m may be secured within the rails 60through a snap fit and/or with adhesives or the like. (See FIGS. 8 and12).

As best depicted in FIGS. 10-12, both the counter actuator 52 and thecam actuator 54 are pivotally mounted within the actuator holder 50through pivot pin 62 which extends through respective openings 52 o, 54o of the counter and cam actuators 52, 54 and through openings 64 of theactuator holder 50. Each of the counter and cam actuators 52, 54 maypivot through a limited range of motion, in both a clockwise and counterclockwise direction about the pivot pin 62. A drive biasing member 66,e.g., a torsion spring, is mounted to the counter actuator 52 tonormally bias the counter actuator 52 to an initial starting conditionor stage of the counter actuator 52. The torsion spring 66 of thecounter actuator 52 has one end 66 a secured in an opening or slot 68 inthe counter actuator 52 and a second end 66 b secured in an opening 70in the actuator holder 50. A return biasing member 72, e.g., a torsionspring, is engagable with the cam actuator 54 to normally bias the camactuator 54 to an initial starting condition or stage. The torsionspring 72 includes one end 72 a which engages the rear or proximalsurface 54 r of the cam actuator 54 and a second end 72 b which isreceived within an opening 74 of the actuator holder 50. Thus, thecounter actuator 52 is biased in a first direction, e.g., counterclockwise, by the torsion spring 66 and the cam actuator 54 is biased ina second direction, e.g., clockwise, by the torsion spring 72.

The cam actuator 54 further includes a pin 76 which is receivable withina pin groove 78 of the counter actuator 52. As best depicted in FIG. 12,a stop rod 80 is mounted within opening 82 of the actuator holder 50 andmay be secured within the rod opening 82 through conventional meansincluding adhesives or the like. The stop rod 80 extends downwardly onlypartially within the channel 56 of the actuator holder 50 to a positionin longitudinal alignment with the counter actuator 52, but above thecam actuator 54. The respective functions of the pin 76 of the camactuator 54 and the stop rod 80 will be discussed in detail hereinbelow.

With reference again to FIGS. 4 and 5, the outer frame 12 includes a cammember 84 which cooperates with the counter and cam actuators 52, 54 torotate the rotatable counter 32. The cam member 84 may be a separatecomponent secured to the outer frame 12 or be integrally formed with theouter frame 12. The cam member 84 defines rear and forward cam surfaces86, 88 and extends through the interior of the rotatable counter 32 inspaced relation therewith to not interfere with rotation of therotatable counter 32. The cam member 84 is also positioned beneath thecounter actuator 52 in longitudinal alignment with the cam actuator 54.The cam member 84 defines an interior surface 84 i.

Referring now to FIG. 13, the loading unit 10 may include a detentmechanism to permit rotational movement of the rotatable counter 32 in afirst direction through actuation of the counter actuator 52 whilepreventing rotational movement in a second opposite direction. In theembodiment of FIG. 13, the detent mechanism may include a spring loadedplunger 90 which is adapted for reciprocal longitudinal movement in thedirections of directional arrows “c₁, c₂”. The plunger 90 may be mountedto the outer frame 12 by conventional means and defines a roundedplunger head 92. The plunger head 92 may selectively engagecorresponding openings or recesses 94 in the distal face 32 d of therotatable counter 32 during rotation of the rotatable counter 32 througheach incremental arc segment of rotation (see also FIG. 6). Each lockingrecess 94 may be in general alignment with a respective internal helicalgroove 42. Upon rotation of the rotatable counter 32, the plunger 90 isforced in a distal direction “c₁” such that the plunger head 92 isreleased from a select locking recess 94 and then returns under theinfluence of its spring bias in proximal direction “c₂” whereby theplunger head 92 is received within the next adjacent locking recess 94in releasable secured relation therewith. In this position of theplunger 90, the rotatable counter 32 is prevented from rotating, and thesuccessive internal helical groove 42 is positioned to receive thecounter actuator 52. Upon movement of the central drive 22 and thecounter actuator 52 through a successive firing stroke, the spring biasof the plunger 90 is overcome causing release of the plunger head 92from the respective locking recess 94 permitting rotation of therotatable counter 32 through a successive incremental arc segment ofrotation. The plunger head 92 and the locking recesses 94 may haveangled or cam surfaces to facilitate entry and exit of the plunger head92 relative to the recesses 94.

FIG. 14 illustrates an alternate detent mechanism to permit movement ofthe rotatable counter 32 in the first direction while preventingmovement in the second direction. In this embodiment, the external wall32 e of the rotatable counter 32 includes a plurality of equi-distallyspaced locking recesses 96 with each recess 96 in general alignment witha respective internal helical groove 42 of the rotatable counter 32. Theouter frame 12 has a ratchet pawl 98 mounted thereto. The ratchet pawl98 is normally biased toward the external wall 32 e of the rotatablecounter 32 to engage a select locking recess 96. Upon rotation of therotatable counter 32, the ratchet pawl 98 moves radially outwardly torelease the select locking recess 96 and then returns under theinfluence of the spring bias to be received within the next adjacentlocking recess 96.

The operation of the loading unit 10 and the counter and lockoutmechanism 30 now will be discussed. With reference to FIGS. 8 and 15-16,the central drive 22 is in its proximal or initial position and theactuator assembly 34 is in its starting condition or stage responsive tothe bias of respective torsion springs 66, 72. In the startingcondition, the pin 76 of the cam actuator 54 is disposed within the pingroove 78 of the counter actuator 52 to bias the counter actuator 52 ina clockwise direction such that the counter and cam actuators 52, 54 aregenerally aligned as depicted in FIG. 16. The loading unit 10 is coupledto the handle assembly 200 whereby a coupler 202 (shown schematically)of the handle assembly 200 couples with the actuator holder 50 which isengaged with the central drive 22 of the loading unit 10. An actuator ofthe handle assembly 200, which is operatively connected to the coupler202, is actuated which initiates the first firing stroke of the centraldrive 22.

With reference to FIGS. 17-18, as the central drive 22 and the actuatorassembly 34 move distally through the firing stroke, the cam actuator 54engages the rear cam surface 86 of the cam member 84, causing the camactuator 54 to pivot or rotate in a counter clockwise direction “m” tothe first pivoted position shown in FIG. 18. During this pivotalmovement of the cam actuator 54, the pin 76 of the cam actuator 54 isreleased from the pin groove 78 of the counter actuator 52 which causesthe counter actuator 52 to also pivot in the counter clockwise directionas indicated by arrow “b” under the influence of torsion spring 66. Thestop rod 80 will engage the rear side of the counter actuator 52 toprevent any further counter-clockwise rotational movement of the counteractuator 52. The cam actuator 54, which is disposed vertically beneaththe stop rod 80, is free to pivot to the position depicted in FIG. 18.In this position of the counter actuator 52, the counter actuator 52 isorientated to an engaged position thereof to engage a first internalhelical groove 42 of the rotatable counter 32.

As depicted in FIGS. 19-20, during continued movement of the actuatorassembly 34 and the central drive 22 through the firing stroke, thecounter actuator 32 traverses the internal helical groove 42 causing therotatable counter 32 to rotate in the direction of directional arrow “d”through a predefined angular segment of rotation. The cam actuator 54traverses the inner surface 84 i of the cam member 84. The central drive22 is advanced (see arrow “t”) until the counter actuator 52 exits theinternal helical groove 42 and clears the rotatable counter 32 asdepicted in FIGS. 21-22. In this position, the counter actuator 52 andthe cam actuator 54 are reset, or return to its initial condition orstage under the influence of the torsion spring 66, 72 with the pin 76of the cam actuator 54 received within the pin groove 78 of the counteractuator 52.

With reference to FIGS. 23-24, subsequent to completion of the firingstroke, the actuator holder 50 and the central drive 22 are movedproximally via, e.g., one of the actuators of the handle assembly 200 orvia a spring bias, to initiate its return stroke. During the returnstroke, the cam actuator 54 engages the forward cam surface 88 of thecam member 84 to rotate the cam actuator 54 in an opposite (e.g.,clockwise) direction to a second pivoted position. The clockwisemovement of the cam actuator 54 causes the counter actuator 52 to alsorotate in the same clockwise direction due to engagement of the pin 76of the cam actuator 54 with the pin groove 78 of the counter actuator52. In particular, the cam actuator 54, through the pin 76, rotates thecounter actuator 52 to a disengaged position within the rotatablecounter 32 where the counter actuator 52 clears the internal helicalgrooves 42 of the rotatable counter 32, thereby permitting the actuatorassembly 34 and the central drive 22 to complete the return strokewithout engagement of the counter actuator 52 with the rotatable counter32. The cam actuator 52 is in contact with the inner surface 84 i of thecam member 84 while the actuator assembly 34 returns to its initialposition.

The actuator assembly 34 and the central drive 22 may undergo successivefiring strokes to, e.g., deliver all of the staples. During each stroke,the counter actuator 52 engages a subsequent internal helical groove 42to cause rotation, e.g., incremental, of the rotatable counter 32 withthe corresponding indicator 40 being viewable by the clinician throughthe window 46 of the outer frame 12. The ratchet or detent mechanism ofFIG. 13 or FIG. 14 will secure the rotatable counter 32 at eachincremental angular position, and then become released from therotatable counter 32 during the next firing stroke and traversingmovement of the counter actuator 52 through the successive internalhelical groove 42.

With reference now to FIGS. 25-26, upon movement of the rotatablecounter 32 through a predefined number of arc segments corresponding toa predefined number of firing strokes of the central drive 22, therotatable counter 32 is eventually rotated to a position where the stop48 is aligned with a lock shelf 100 of the central drive 22. In thisposition, the central drive 22 is locked and prevented from moving in adistal direction, i.e., incapable of firing. The lock position maycorrespond to depletion of the staples, e.g., in the end effector orstaple assembly 300.

Thus, during use, the clinician can monitor the staple supply within theend effector 300 and anticipate when the supply will be exhausted. Whenthe loading unit 10 is completed, the clinician can release the loadingunit 10 from the handle assembly 200 and, if necessary, connect a newloading unit 10 to complete the procedure.

Referring now to FIG. 2, details of one exemplative handle assembly 200for use with the loading unit 10 will be described. The handle assembly200 includes a housing 204 and an elongated body 206 extending from thehousing 204. The housing 204 includes a stationary handle 208 and amovable handle 210 which is pivotally supported to the housing 204 andis operatively connected to a control rod 212 extending at leastpartially through the elongated body 206. The control rod 212 iscouplable to the central drive 22 of the loading unit 10 via, e.g., thecoupling 202, upon mounting of the loading unit 10 to the handleassembly 200. Pivotal movement of the movable handle 210 causeslongitudinal translation of the control rod 212, which also mayapproximate the staple cartridge 302 and the anvil 304, and cause firingof the staples. A pair of retraction knobs 214 may be mounted to thehousing 204 and also operatively coupled to the control rod 212. Theretraction knobs 214 may be utilized to retract the control rod 212 andthe central drive 22 of the loading unit 10 subsequent to each firingstroke. The handle assembly 200 may further include an articulationlever 216 which is couplable to the translating rod 28 (FIG. 3) of theloading unit 10. The articulation lever 216 may be manipulated toarticulate the end effector or staple assembly 300. A rotatable knob 218may also be provided to cause rotation of the elongated body 206 and atleast the end effector 300 of the loading unit 10.

Other handle arrangements are also envisioned including single actuatorhandles, powered, electro-mechanical or the like. The loading unit canalso be configured for use with robotic surgical systems. One example ofa handle assembly 200 suitable for use with the loading unit 10 isdisclosed in commonly assigned U.S. Pat. No. 8,070,033 to Millman etal., the entire contents of which are hereby incorporated by referenceherein.

With reference now to FIGS. 27-30, further details of the end effector300 of the loading unit will be discussed. In the embodiment of FIG. 1,the end effector 300 is a staple assembly including the staple cartridge302 and the anvil 304 which are adapted to pivot relative to each otherbetween open and approximated conditions depicted respectively in FIGS.27-28. As best depicted in FIGS. 29-30, the staple cartridge 302 mayinclude one or more staple magazines 306 with each magazine having aplurality of staples 308. Each magazine 306 may further include a staplecam 310 which moves in a direction generally orthogonal to the axis “k”to eject the staples 308 toward the anvil 304. At least one or morestaple pushers 312 are at least partially disposed within the staplecartridge 302 and operatively coupled to the central drive 22 of theloading unit 10. (see also FIGS. 27-28) The staple pusher(s) 312 may beoperatively couplable or engagable with, or a component of, theactuation sled 24 of the central drive 22. Movement of the central drive22 through a complete firing stroke, e.g., actuation of the movablehandle 210 of the handle assembly 200, will cause the staple pusher(s)312 to engage the staple cams 310 to eject the staples 308 for passagethrough tissue to be crimped by the anvil 304. In one embodiment, thestaple cartridge 302 will deliver at least two or more linear rows ofstaples. Simultaneously therewith, the knife 26 of the actuation sled 24may sever the tissue between the linear rows of staples 308. Thereafter,the staple pusher 312 is returned through a return stoke to the initialposition of FIG. 27 via, e.g., retracting movement of the retractionknobs 214 of the handle assembly 200. In this position, the movablehandle 210 may be actuated to advance the control rod 212 and thecentral drive 22 of the loading unit 10 to deliver another set ofstaples 308 in sequence.

One exemplative staple assembly which may be incorporated with theloading unit 10 is disclosed in commonly assigned U.S. patentapplication Ser. No. 14/279,781 to Kostrzewski, filed May 16, 2014, theentire contents of which disclosure are hereby incorporated by referenceherein.

Although the end effector 300 is described as a stapling assembly, theloading unit 10 with the counter and lockout mechanism 30 mayincorporate other types of end effectors with different functions. Forexample, the end effector 300 may be adapted to deliver any type offasteners including clips, needles, medicant capsules or the like, andmay be adapted to perform different stapling functions including end toend or circular fastening.

Persons skilled in the art will understand that the devices and methodsspecifically described herein and illustrated in the accompanyingdrawings are non-limiting exemplary embodiments. It is envisioned thatthe elements and features illustrated or described in connection withone exemplary embodiment may be combined with the elements and featuresof another without departing from the scope of the present disclosure.As well, one skilled in the art will appreciate further features andadvantages of the disclosure based on the above-described embodiments.Accordingly, the disclosure is not to be limited by what has beenparticularly shown and described.

What is claimed is:
 1. A surgical loading unit, which comprises: anelongate outer frame defining a longitudinal axis and having proximaland distal ends; an end effector mounted to the distal end of the outerframe; a drive at least partially disposed within the outer frame andoperatively coupled to the end effector, the drive adapted forlongitudinal movement through a plurality of sequential firing strokesto operate the end effector; a rotatable counter mounted to the outerframe and adapted for rotational movement about the longitudinal axis,the rotatable counter having visual indicators for providing visualindicia corresponding to a number of firing strokes completed by thedrive; a counter actuator mounted to the drive and dimensioned to engagethe rotatable counter to cause rotational movement of the rotatablecounter through an arc segment of rotation during each firing stroke ofthe drive; and a cam actuator mounted to the drive and dimensioned tooperatively engage the counter actuator to cause release of the counteractuator from the rotatable counter upon longitudinal movement of thedrive through each successive return stroke.
 2. The surgical loadingunit according to claim 1 wherein the outer frame defines a windowthrough which a visual indicator of the rotatable counter is visible. 3.The surgical loading unit according to claim 1 wherein the rotatablecounter includes a stop, the stop positionable to engage the drive uponrotatable movement of the rotatable counter through a predeterminednumber of arc segments corresponding to a predetermined number of firingstrokes completed by the drive.
 4. The surgical loading unit accordingto claim 1 wherein the rotatable counter includes internal helicalgrooves, the counter actuator engagable with the helical grooves tocause rotational movement of the rotatable counter.
 5. The surgicalloading unit according to claim 4 wherein the counter actuator isadapted to pivot relative to the drive between an engaged position to bereceived within one of the helical grooves of the rotatable counterduring each firing stroke of the drive and at least a disengagedposition disengaged from the one of the helical groove during eachreturn stroke of the drive.
 6. The surgical loading unit according toclaim 5 wherein the counter actuator is normally biased toward theengaged position.
 7. The surgical loading unit according to claim 5wherein the cam actuator is adapted to pivot between an initial positionand first and second pivoted positions, the cam actuator permitting thecounter actuator to assume the engaged position of the counter actuatorwhen the cam actuator is in the first pivoted position, and moving thecounter actuator to the disengaged position of the counter actuator whenthe cam actuator is in the second pivoted position.
 8. The surgicalloading unit according to claim 7 wherein the cam actuator is normallybiased toward the initial position, and pivots in a first direction toassume the first pivoted position and pivots in a second direction toassume the second pivoted position.
 9. The surgical loading unitaccording to claim 8 wherein the outer frame includes a cam having rearand forward cam surfaces, the cam actuator engaging the rear cam surfaceduring movement of the drive through each firing stroke to move the camactuator to the first pivoted position thereby permitting the counteractuator to assume the engaged position, the cam actuator engaging theforward cam surface during movement of the drive through each returnstroke to orient the cam actuator in the second pivoted position therebymoving the counter actuator to the disengaged position.
 10. The surgicalloading unit according to claim 4 including a detent mechanism having adetent member mounted relative to the outer frame and locking recessesassociated with the rotatable counter, the detent member engagable witha respective locking recess subsequent to each firing stroke of thedrive to maintain the rotatable counter at a desired rotationalposition, and adapted to release the respective locking recess uponmovement of the drive through each successive firing stroke.
 11. Thesurgical loading unit according to claim 1 wherein the end effectorincludes a fastener assembly having a plurality of fasteners, at leastone fastener being ejected upon movement of the drive through a firingstroke.
 12. A surgical loading unit, which comprises: an elongate outerframe defining a longitudinal axis and having proximal and distal ends,the proximal end being adapted for coupling with the handle assembly; astaple assembly mounted to the distal end of the outer frame, the stapleassembly including a staple cartridge housing a plurality of staples andan anvil, the anvil adapted for movement relative to the staplecartridge between an open position to receive tissue and an approximatedposition to clamp tissue; a drive at least partially disposed within theouter frame and operatively couplable to the staple assembly, the driveadapted for longitudinal movement through a plurality of sequentialstrokes to eject at least one staple from the staple cartridge forcrimping by the anvil when in the approximated position thereof; arotatable counter and lockout mechanism including: a rotatable countermounted to the outer frame and adapted for rotational movement throughan arc segment of rotation upon movement of the drive through eachfiring stroke; at least one visual indicator associated with therotatable counter for providing visual indicia corresponding to a numberof firing strokes completed by the drive; a lock member positionable toengage the drive upon rotatable movement of the rotatable counterthrough a predetermined number of arc segments corresponding to apredetermined number of firing strokes completed by the drive; a counteractuator mounted to the drive and dimensioned to engage the rotatablecounter to cause rotational movement of the counter through an arcsegment of rotation during each firing stroke of the drive; and a camactuator mounted to the drive and dimensioned to operatively engage thecounter actuator to cause release of the counter actuator from therotatable counter upon longitudinal movement of the drive through eachsuccessive return stroke.
 13. The surgical loading unit according toclaim 12 wherein the counter actuator is adapted to pivot relative tothe drive between an engaged position to couple with the rotatablecounter during each firing stroke of the drive and at least a disengagedposition disengaged from the rotatable counter during each return strokeof the drive.
 14. The surgical loading unit according to claim 13wherein the rotatable counter includes internal helical grooves, thecounter actuator engagable with one helical groove when in the engagedposition to cause rotational movement of the rotatable counter duringeach drive stroke, and disengaged from the one helical groove when inthe disengaged position during each return stroke.
 15. The surgicalloading unit according to claim 14 wherein the cam actuator is adaptedto pivot between an initial position and first and second pivotedpositions, the cam actuator permitting the counter actuator to assumethe engaged position of the counter actuator when the cam actuator is inthe first pivoted position, and moving the counter actuator to thedisengaged position of the counter actuator when the cam actuator is inthe second pivoted position.
 16. The surgical loading unit according toclaim 12 including a detent mechanism having a detent member mountedrelative to the outer frame and locking recesses associated with therotatable counter, the detent member engagable with a respective lockingrecess subsequent to each firing stroke of the drive to maintain therotatable counter at a desired rotational position, and adapted torelease the respective locking recess upon movement of the drive througheach successive firing stroke.